On May 5, 2010, Obey announced that he would not seek reelection to Congress in November 2010. He left Congress in January 2011, and was succeeded by Republican Sean Duffy. He began working for Gephardt Government Affairs, a lobbying firm founded by former U.S. House Majority Leader Dick Gephardt, in June 2011.[2]

Obey grew up as a Republican. However, he was so angered after seeing his teachers falsely branded as Communists by backers of Joseph McCarthy that he became a Democrat in the mid-1950s, sometime between the ages of 16 and 18.[5]

Obey was the longest-serving member of either house of Congress in Wisconsin's history. He was also the third longest-serving member of the House, after fellow Democrats John Dingell and John Conyers, both of Michigan.

In Congress, Obey chaired the commission to write the House's Code of Ethics. Among the reforms he instituted was one requiring members of the House to disclose their personal financial dealings so the public would be made aware of any potential conflicts of interest. Obey served as chairman of the House Appropriations Committee from 2007 to 2011; he briefly chaired this committee from 1994 to 1995 and served as its ranking Democrat from 1995 to 2007. He also chaired its Subcommittee on Labor.

Obey was one of the most liberal members of the House; he considers himself a progressive in the tradition of Robert La Follette.[6] Obey had risen to the position of fifth ranking House Democrat since his party retook control of Congress.

Obey also is remembered for being the congressman who intervened when fellow Democrat Harold Ford, Jr. approached Republican Jean Schmidt on the House floor in 2005. Ford was upset because Schmidt had called Congressman John Murtha a coward for advocating a redeployment of American forces in Iraq.

Obey holds a critical view of the mainstream American news media, as evidenced by his words on June 13, 2008, upon the sudden death of NBC News Washington Bureau Chief Tim Russert. Obey said of Russert: "Tim Russert's death is not just a body blow for NBC News; it is a body blow for the nation and for anyone who cherishes newsmen and women who have remained devoted to reporting hard news in an era increasingly consumed by trivia."[7] Dave Obey announced an end to his congressional career on May 5, 2010, with press releases being released on May 6. ."[8]

On June 30, 2010, Obey proposed an amendment to a supplemental war spending bill that would allocate $10 billion to prevent expected teacher layoffs from school districts nationwide. The amendment, which passed the House on July 1, 2010, proposed siphoning off $500 million from the Race to the Top fund as well as $300 million designated for charter schools and teacher incentive pay.[9] In response, the White House released a statement threatening a veto if the bill is passed by the Senate.[10]

Obey was elected to the House to replace eight-term incumbent RepublicanMelvin R. Laird, who was appointed Secretary of Defense under President Richard Nixon. Obey, only 30 when he was elected, became the youngest member of Congress upon taking his seat, as well as the first Democrat ever to represent the district. He was elected to a full term in 1970 and has been reelected 18 times. He has only faced serious opposition twice. In 1972, during his bid for a second full term, his district was merged with the neighboring 10th District of Republican Alvin O'Konski, a 15-term incumbent. However, Obey retained 60 percent of his former territory, and was handily reelected in subsequent contests.

In 1994, Obey only won reelection by seven points as the Democrats lost control of the House during the Republican Revolution.

Obey was expected to run in 2010, having raised a warchest of $1.4 million. However, Obey was facing tough poll numbers in his district, plus his age and the death of close colleague John Murtha and his frustration with the White House convinced him to bow out of the race.[13][14]

Upon his retirement, the seat was won by Republican Sean Duffy who defeated Democrat State Senator Julie Lassa.